This invention relates in general to technology for detecting hidden features within an opaque environment and, more particularly, to techniques for detecting such hidden features without physical contact with the structure or material of the opaque environment.
There are a variety of situations in which it is desirable to be able to detect a hidden feature, characteristic or object disposed within an opaque environment, without any direct physical contact with the material or structure of the opaque environment. One specific example is the detection of landmines that are buried a short distance between the surface of the earth. Pre-existing systems have been developed for the purpose of attempting to detect features within an opaque environment, and have been generally adequate for their intended purposes. However, these pre-existing systems have not been satisfactory in all respects.
In this regard, pre-existing systems typically require a relatively short stand-off distance for interrogation, and have relatively high false alarm rates, including both false positives and false negatives. Further, pre-existing systems tend to have limited inspection rates, such as the rate-of-advance along the ground of a vehicle carrying a system that is being used to detect buried landmines. Moreover, some pre-existing systems are configured only to detect objects, without necessarily identifying them. Other systems that have some identification capabilities do not tend to provide accurate and efficient identification of objects.
From the foregoing, it may be appreciated that a need has arisen for a method and apparatus for efficient and accurate detection and identification of features disposed within an opaque environment. One form of the invention involves: selecting an excitation signal; transmitting the excitation signal; receiving a signal which contains information produced by a remote object in response to the excitation signal; evaluating the information for the purpose of identifying the remote object; adjusting the excitation signal based on the evaluation of the information; and repeating the transmitting, receiving and evaluating with the adjusted excitation signal.
A different form of the invention involves: transmitting an excitation signal; transmitting an optical probe signal; receiving an optical signal which is a reflection of the probe signal and which contains information produced by a remote object in response to the excitation signal; and evaluating the information for the purpose of identifying the remote object.